Bubble deck fractionator useful for small scale fractionation



Dec. 20, 1966 R. A. LENGEMANN ET AL 3,293,149

BUBBLE DECK FRACTIONATOR USEFUL FOR SMALL SCALE FRACTIONATION Filed Aug. so, 196s Hol/ow Dec/f Support A TTOR/VEYS United States Patent O BUBBLE DECK FRACTINATR USEFUL FR SMALL SCALE FRACTIUNATIQN Robert A. Lengemann, Park Ridge, and Leslie C. Hardison, Arlington Heights, Ill., assignors to Universal Gil Products Company, Des Plaines, Ill., a corporation of Delaware Filed Aug. 30, 1963, Ser. No. 305,666

7 Claims. (Cl. 202--158) The present invention relates to an improved small fractionator design, and more particularly to an improved design and construction which utilizes small bubble decks and has the ability to maintain constant efficient performance over a wide range of throughputs.

Fractionation within small scale equipment, such as utilized in pilot plant type of units, is generally difficult and results have been far from optimum, particularly in connection with high temperature metallic units which have used packinfr material to effect the vapor liquid contacting. In addition there has been considerable dithculty in effecting satisfactory insulation for small sized fractionating units, such that heat losses have been high and adiabatic operation difficult to obtain.

It is thus an object of the present invention to provide an improved small scale fractionating column design which is adapted for encasement within an insulating enclosure and is capable of obtaining enhanced fractionating results over varying ranges of operations.

It is also an object of the present invention to provide an improved design which utilizes small sized bubble decks and novel means for supporting them within a vertically elongated column.

In one embodiment, the improved small capacity fractionator comprises in combination, a vertically elongated housing having at least one intermediately positioned fluid inlet thereto and at least two fluid outlets therefrom for the discharge of separate fractions, means for supplying heat to uid maintained within the lower portion of the housing, and a plurality of vertically spaced bubble decks within the housing, with each of the decks having a weir and downpipe means for downward flow of liquid and a plurality of spaced vapor openings therethrough, accompanying movable ball and seat means for the top of each of the vapor openings, and in addition each of the decks have perforate screen means positioned closely thereabove whereby to preclude the displacement of the movable ball means above each vapor opening and its seat means.

One of the improved aspects for small sized bubble decks has been the incorporation of ball check means in combination with seat means provided at the top of each of the vapor openings through each deck in the column. A lightweight ball of refractory material serves to permit upward ow of vapor through each of the decks while at the same time precluding downward flow of liquid which will flow across each deck to the top of the downspout means for transfer to a next lower deck. The size and weight of each ball utilized as a check valve means will, of course, be correlated with the spacing between decks and the upward vapor flow or range of vapor pressure to be encountered in a particular column.

Still another improved design feature of the new fractionating column utilizes a deformed screen member over the top of each bubble deck so as to effect the holding of the ball check members in their proper positioning over each opening. The screening is preformed with raised or dimpled portions to set over the ball check means to allow some upward movement of each ball to in turn permit an upward Vapor ow through each deck. The perforate screening may be welded or otherwise attached to each deck, with a preferred embodiment extending over the entire deck area so that it will serve to not only control the size of upiiowing Vapor bubbles, but will serve to equalize the liquid flow across the deck and enhance vapor-liquid contacting at each level.

A particular improved design feature is also embodied in the use of a central hollow supporting member extending downwardly through the top end of the fractionating column or housing to the lowermost of the plurality of superimposed decks. Each deck is attached at predetermined vertically spaced distances to the hollow tube, or alternatively, each of the decks may be held by the supporting rod with the use of spacer means between decks and the lowermost of the series being fixedly attached to the rod. This arrangement permits the entire assembly of bubble decks to be lowered into the fractionator housing and at the same time permits the insertion of thermocouple means downwardly into the interior portion of the fractionator at any desired level by utilizing the interior portion of the hollow supporting rod.

Additional construction features and advantages in connection therewith are set forth and referred to in the accompanying drawing and the following description thereof.

FIGURE l of the drawing is a diagrammatic elevational view of the improved small scale fractionating column with a plurality of vertically suspended small sized bubble decks therein effecting the desired vapor liquid contacting.

FIGURE 2 of the drawing is a sectional plan View indicating the top of one of the bubble decks in the column, as indicated by the line 2 2 in FIGURE l.

FIGURE 3 of the drawing is a sectional elevational view through a deck and downspout means, as indicated by line 3-3 in FIGURE 2.

FIGURE 4 of the drawing shows, in an enlarged sectional view, the arrangement of a ball check member in its seating means with the top of each vapor opening through the bubble deck members.

Referring now to the drawing, and particularly to FIG- URE l, there is shown a vertically positioned housing 1 having an upper hollow conduit section 2 with an end closure member 3 and a vapor outlet nozzle 4. A reflux inlet nozzle 5 is also provided at the top of the column above a rst deck 6. A feed inlet nozzle 7 is shown at an intermediate point in the column, while a lower outlet line 8 provides means for the discharge of the bottoms fraction. The heating of the bottoms liquid in the column is provided by means of withdrawal line 9, a riser line 10 and an electric heating coil 11. The power supply to the coil 11 may be conventional and is not indicated in the present drawing.

A plurality of the improved decks 6, together with downpipes 12, are merely shown diagrammatically in FIGURE 1 as being spaced vertically one from another within the interior of the housing 1 and supported by a hollow deck supporting tube 13. The tube 13 passes axially through the top closure member 3 for the enlarged tube 2 and through the center of each of the decks 6 to become attached to the lowermost of the decks 6. Thus, all of the decks are held `and positioned at predetermined elevations within the column 1 to accommodate both the stripping and rectifying sections of the column. In the present embodiment, a top head 14 for the column 1 is made removable by reason of a flanged connection with the top portion of the column; however, the plurality of trays or decks may be positioned Within the column prior to the welded attachment to the top head to the column where a flanged connection is undesirable.

There is also indicated in connection with FIGURE l of the drawing a spaced outer shell member 15 which is adapted to encase or hold a suitable insulating material around the column 1. For example, the shell 15 may be constructed to maintain a vacuum in combination with a plurality of heat radiation shields which are positioned concentrically around column 1 within the housing 15. However, it is not intended to limit the present invention to the use of any one type of insulating means although, as may be noted, the present improved small scale fractionator design and construction is particularly adapted for encasement within suitable insulating means to provide a highly efficient adiabatic operation.

Referring now more lparticularly to FIGURES 2 and 3 of the drawing, there is shown the placement of a plurality of vapor openings 16 with accompanying enlarged tapered sections 17 which serve as a seat for movable ball members 1S. In operation, each ofthe vapor openings 16 permit the upward dow of vapor rising through the column 1 -at a controlled rate effecting the slight lifting of ball members 18 as they pass to a next higher deck section and come into Contact with a down-flowing liquid stream passing across the upper surfaces of the deck 6. In a typical bubble tray type of operation, the liquid passes from the lower end of a superposed downpipe 12 over and around the ball members 18 and the vapor openings 16 to flow over a weir, or open raised inlet end 19, for each downpipe section.

It is not intended to limit the new deck design to the use of any particular number of vapor openings nor to any one predetermined size, inasmuch as the size and spacing may be varied in accordance with the type of feed being fractionated in the column. Various types of ball check members 18 may also be utilized within the scope of the present invention, with the size and Weight of the members being correlated with the size of the vapor openings and the vapor pressure being exerted between the spaced trays. In all cases the ball check members, as weil as the deck member, downpipes, etc., shall be formed of a metal or other refractory material capable of withstanding high temperature operations. Thus, the ball members 18 may be formed of glass, ceramic materials, hollow metals and the like.

In the embodiment of FIGURE 3, the downpipe 12 is provided with a lower open topped distributing tray 20 which is welded, soldered or otherwise attached to the lower open end of the downpipe 12. Thus, a downfiowing liquid stream through the column will be permitted to be more widely distributed over the rim of the tray member 20 and onto the next lower tray member 6.

The embodiment of FIGURE 3 also indicates that each of the deck members 6 are spaced one from another vertically by the use of hollow spacer members 21 which slide over 4the inner supporting tube member 13 between deck members 6. In other words, the deck members 6 and spacers 21 may be alternately placed or stacked on and over the inner hollow tubular member 13 which is xedly attached to the lowermost deck 6 such that the latter supports the entire vassembly of the superimposed plurality of decks. Also, as hereinbefore indicated, in lieu of spacer members 21, each of the deck members may be welded or otherwise attached directly to -the hollow member 13 at predetermined spaces such that the entire assembly is supported from tube 13 within the central portion of column 1.

Still further, in accordance with an improved fractionator design, and particularly for pilot plant operations, the center support tube 13 is hollow throughout its entire length and projects outwardly from the upper end of the column 1 and any enclosing shells or housings such that thermocouples or other instrumentation is inserted internally into the interior of chamber 1 in the manner of a thermowell. Thus, for example, a temperature reading may be obtained at any desired level throughout the .height of the column 1 by inserting one or more temperature sensitive elements into the interior of member 13.

Upon reference to FIGURE 4 of the drawing, there will be noted another advantageous feature of the improved bubble deck design, wherein the deformed perforate member, such as screening 22, is provided over the top surface of deck 6 and the ball check members 18 to preclude their displacement from seats 17 on the top face of the deck. The screening or perforate means 22 may be dimpled or otherwise deformed at points 22' over each i of the vapor openings and members 18 such that the latter are free to move slightly upwardly from the seats 17 and vapor openings 16. There is a particular advantage in the present design which utilizes screening, such as 22, across the entire upper face of the deck 6 in that there is an increased retention and spread of the downflow liquid across the base of the deck and a resulting improved uniform contact with the rising vapor streams through each of the plurality of vapor openingsV spread across the face of the deck plate. Still further, it appears that one of the major problems encountered in the operation of a small size laboratory or pilot plant type of fractionator is the prevention of large up-tlowing vapor bubbles. The screening serves to break up the vapor stream and provide small bubbles in the column. Thus, there is a triple function for the screen member to serve as a hold-down member, a liquid distributor and a vapor distributor which can assist contacting and overall fractionation efficiency. Such screening may be tackwelded or otherwise attached to the upper face of each plate 6 and it is not intended to limit the method of attachment to any one means, nor to limit the type of screening to any one particular wire land mesh size inasmuch as there may be variations in accordance with the size of the fractionating column and with the quantity of liquid flow anticipated from the type of feed stream being fractionated.

It is realized that there are various types of lift members which have been utilized in connection with bubble deck designs for fractionating columns. However, such designs are not adaptable to small scale fractionating equipment, which, Afor example, may be sized to the order of one inch in diameter, such that vapor openings are in turn of the order of Q6-inch to 3/16-inch in diameter. However, the provision of tapered seat means on the upper face of the deck plate and the use of accompanying ball check members such as set forth and described hereinbefore, in combination with a screen retaining member, have served to provide efficient fractionation over wide operating conditions with various feed stocks. It has further been determined that the deck supporting means comprising a hollow supporting tube provides a novel Amethod of accurately positioning bubble trays at predetermined points and at the same time permitting insertion of accompanying instrumentation without the necessity for added extraneous nozzles or thermowell openings, etc., around the main body of the fractionating column.

We claim as our invention:

1. An improved fractionator comprising in combination,

(a) a vertically elongated housing having at least one fluid inlet thereto and at least two uid outlets therefrom to discharge separated fractions,

(b) means supplying heat to fluid maintained in the lower portion of said housing, and

(c) a plurality of vertically spaced bubble decks within said housing,

(d) each of said decks having a weir and downpipe means, a plurality of spaced vapor openings therethrough, and an accompanying movable ball and seat means for the top of each of said vapor openings, and in addition,

(e) each of said decks having perforate screen means extending substantially over and in contact with the entire upper face of the deck and being deformed above each of said movable ball means at said vapor openings, whereby to enhance vapor-liquid ow and contacting and to preclude each of the movable ball means above each vapor opening from being displaced from its seat means on the upper face of a deck.

2. .T he fractionator of claim 1 further characterized in that said spaced bubble decks are supported at predetermined spaced distances from a hollow supporting rod ex plate member having a weir and downpipe means, a plurality of spaced vapor openings through said plate member, an accompanying movable ball and seat means for the top of each of said vapor openings, and a perforate screen means extending substantially over land in contact with the entire upper face of the deck and being upwardly deformed above each of said movable ball means at said vapor openings to permit a small lifting of each ball means for upward vapor passage.

3. The fractionator of claim 1 further characterized in that said ball means are formed of ceramic material.

4. The fractionator of claim 1 further characterized in that said ball means are hollow.

5. A fractionator bubble tray assembly comprising a 10 6. An improved small capacity fractionato-r compri-sing in combination,

(a) a vertically elongated housing having at least one uid inlet thereto and at least two iluid outlets therefrom to discharge separated fractions,

(b) means supplying heat to fluid maintained in the lower portion of said housing,

(c) a plurality of vertically spaced bubble decks within said housing, each of said decks being unattached to said housing and each of said decks having a weir and downpipe means, a plurality of spaced vapor openings therethrough, and an accompanying movable ball and seat means for the top of each of said vapor openings,

(d) each of said decks having perforate screen means extending substantially over and in contact with the enti-re upper face of the deck and being deformed above each of said movable ball means at said vapor openings, whereby to enhance vapor-liquid ow and contacting and to preclude each of the movable ball means above each vapor opening from being displaced from its seat means on the upper face of a deck, and

(e) means supporting said spaced bubble decks at predetermined vertically spaced distances comprising a hollow supporting rod extending axially down through said housing and through said plurality of decks, with said hollow supporting rod extending externally from said housing whereby instrumentation may be inserted through said hollow rod into and uninterruptedly along the interior of said housing.

7. The fractionator of claim 6 further characterized in that only the lowermost of said bubble decks is xedly attached to said supporting rod and the remaining bubble decks are supported and spaced apart by respective hollow spacer members removably inserted over said supporting rod with a spacer member positioned between and bearing against successive adjacent bubble decks, whereby said lowermost bubble deck supports the resulting entire assembly of the superimposed plurality of decks.

References Cited by the Examiner UNITED STATES PATENTS 2,090,534 8/1937 Kilayko. 2,609,277 9/1952 McNamara 261-114 2,843,714 7/1958 Stanton 202-160 3,179,389 4/1965 Nutter.

FOREIGN PATENTS 1,918 8/1921 France.

1,330,217 5/1963 France.

485,050 10/ 1929 Germany.

NORMAN YUDKOF F, Primary Examiner.

F. E. DRUMMOND, Assistant Examiner. 

1. AN IMPROVED FRACTIONATOR COMPRISING IN COMBINATION, (A) A VERTICALLY ELONGATED HOUSING HAVING AT LEAST ONE FLUID INLET THERETO AND AT LEAST TWO FLUID OUTLETS THEREFROM TO DISCHARGE SEPARATED FRACTIONS, (B) MEANS SUPPLYING HEAT TO FLUID MAINTAINED IN THE LOWER PORTION OF SAID HOUSING, AND (C) A PLURALITY OF VERTICALLY SPACED BUBBLE DECKS WITHIN SAID HOUSING, (D) EACH OF SAID DECKS HAVING A WEIR AND DOWNPIPE MEANS, A PLURALITY OF SPACED VAPOR OPENINGS THERETHROUGH, AND AN ACCOMPANYING MOVABLE BALL AND SEAT MEANS FOR THE TOP OF EACH OF SAID VAPOR OPENINGS AND IN ADDITION, 